Abstract

We investigate effects of different mechanisms on coupling efficiency between strip waveguides and the slow light mode in photonic crystal waveguides (PCWs). Both numerical simulations and experimental results show that group index tapering improves strip-PCW butt-coupling efficiency when compared to a direct coupling between a strip waveguide and a high- PCW. However, coupling efficiency is even higher when an intermediate low- PCW is used to couple from a strip waveguide to a high- PCW without an tapering. Our results suggest that the role of evanescent mode is more dominant in efficient coupling between two PCWs with large mismatch.

Received 29 November 2010Accepted 05 January 2011Published online 21 January 2011

Acknowledgments:

This research was supported by the AFOSR Multi Disciplinary University Research Initiative (MURI) under Grant No. FA9550-08-1-0394 and AFOSR Small Business Technology Transfer (STTR) under Grant No. FA9550-11-C-0014.